As in the original game, customising weapons and upgrading them is a core aspect of The 40th Day. This is all handled from within the game, as long as you're not engaged in combat. As well as buying new weapons for use in your primary, secondary and special slots, there are also extras such as grenades and perks - increasing your primary ammo and adding extra grenade slots, amongst others. Once you've got your desired weapons it's time to upgrade them, increasing their accuracy, ability to attract aggro and more. Any bought silencers and scopes can be added or removed on the fly, so there's no need to play through an entire section of the game with a silenced pistol if the situation doesn't require it. All the upgrade and customisation options will be great for gun nuts and those who want to bling-out their weapons, and for everyone else it's a quick and easy way to get an upper hand on the battlefield.
Cooperative gameplay mechanics are the focus, with the Aggro system once again joined by assisted jumps (used to climb up to or over high objects), reviving your fallen partner (drag to safety, then give medical attention), co-op shielding (grab a shield and let your partner piggyback in behind you), back to back (pre-determined moments in which you're rooted to the spot, firing at enemies while back to back with your buddy) and more. The aforementioned taking enemies hostage move allows your friend to go in and kill or restrain other enemies who have surrendered, although it's important to grab the most high ranking solder - else the rest of the group might not care if your captive is shot. From time to time this mechanic proved to be rather fiddly, with Salem and Rios fumbling over their moves and the enemies spotting them. When it works, though, it's a smart way to lessen the trigger-happy kill everything that moves gameplay.
Other new aspects to the gameplay include carrying out mock surrenders. This is quite cool the first time around, but do it over and over again and it gets a bit tiresome. After kneeling to pretend you're about to surrender, you can whip out your gun in slow motion and mow down the enemy soldiers. If you clear certain groups of enemies without them alerting their colleagues you often gain access to a weapons cache, so it pays to make the most of these situations.
As a duo you're frequently presented with situations in which you can choose to do things in one of two ways, often without much time to think. Your choices will have an impact on your morality rating for each level and the weapons you gain access to, while also potentially earning you some instant cash. But things aren't as clear cut as they seem, with the game showing you the result of your choices through comic-book-style cutscenes. No doubt EA was trying to convey how unpleasant the world can be, but it's somewhat depressing to see most of your caring choices cause terrible consequences. Other than the cash and weapons gained, your choices have a disappointing lack of impact. One character early on suggests you might run into him again as a result of your actions, but seconds later you're shown what happens to him, making his reappearance impossible. After a while you simply won't care any more.
There's no doubt that The 40th Day is an improvement on the original game in a number of key areas, but the campaign can be breezed through in under five hours if you know what you're doing. There are four multiplayer modes included, catering for a maximum of 12 players. In a twist to the usual multiplayer shooter gameplay mechanics, deathmatch sees teams of two working together, while the Extraction mode is the now popular survival game type that sees you and three others fending off wave after wave of enemies. Warzone and Control are more standard, with teams of six competing to accomplish missions and hold control points on the map. While all game types offer some good fun, Army of Two's gameplay doesn't make for a top-class multiplayer experience.
The 40th Day definitely excels in its presentation. The visuals have markedly improved on the first game, delivering large, detailed environments and some excellent lighting. The frame rate stumbles from time to time, and overall it isn't up to the bar set by the likes of Killzone 2 and Uncharted 2, but the game is full of thrilling set-pieces, explosions and impressive character models. Salem and Rios' models are both a huge step up on their design in the first game, and now you really get a sense of them being different - one lean, the other a hulking brute of a man. Audio work is great, with the voice acting throughout being excellent - we just wish EA hadn't used Nolan "Nathan Drake" North for Salem. Is there any game this guy isn't in these days?
Army of Two: The 40th Day is a solid, entertaining third-person shooter, best played with a friend, but it's not quite the big advancement over the original it could have been. It's a more cohesive game, thanks to its location and more believable main characters, but the AI still disappoints at times and the new morality system misses far more than it hits. It's also incredibly short, and without a top-tier multiplayer component to turn to, your fun will likely be over very quickly. Good, but still not the blockbuster franchise EA no doubt wants it to be.